CVE-2017-4950 in Workstation
Summary
by MITRE
VMware Workstation and Fusion contain an integer overflow vulnerability in VMware NAT service when IPv6 mode is enabled. This issue may lead to an out-of-bound read which can then be used to execute code on the host in conjunction with other issues. Note: IPv6 mode for VMNAT is not enabled by default.
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Analysis
by VulDB Data Team • 01/29/2021
The vulnerability identified as CVE-2017-4950 represents a critical integer overflow flaw within VMware Workstation and Fusion products that specifically affects the VMware NAT service when IPv6 mode is enabled. This vulnerability resides in the network address translation functionality that facilitates communication between virtual machines and the host system. The issue manifests as an integer overflow condition that occurs during the processing of IPv6 network packets within the NAT service component, creating a scenario where an attacker can manipulate input data to cause the system to perform operations beyond the bounds of allocated memory regions.
The technical implementation of this vulnerability stems from insufficient input validation and boundary checking within the IPv6 handling code path of the VMware NAT service. When IPv6 mode is enabled, the system processes incoming network packets through a code path that fails to properly validate integer values used for buffer indexing or packet size calculations. This allows an attacker to craft specially formatted IPv6 packets that trigger an integer overflow condition, resulting in an out-of-bounds read operation. The out-of-bounds memory access can potentially expose sensitive data or allow an attacker to manipulate memory contents in ways that could be leveraged for code execution.
The operational impact of this vulnerability extends beyond simple memory corruption, as it creates a potential privilege escalation vector when combined with other existing vulnerabilities. An attacker who can successfully exploit this integer overflow condition gains the ability to execute arbitrary code on the host system with the privileges of the VMware process, which typically runs with elevated permissions. This represents a significant security risk because it allows attackers to bypass the isolation typically provided by virtualization environments and potentially compromise the entire host system. The vulnerability requires specific conditions to be exploited, namely the explicit enabling of IPv6 mode for VMNAT, but once these conditions are met, the attack surface becomes considerably more dangerous.
The exploitability of CVE-2017-4950 aligns with CWE-190, which specifically addresses integer overflow conditions that can lead to memory corruption and arbitrary code execution. This vulnerability also maps to ATT&CK technique T1059, which covers command and scripting interpreter usage, as the successful exploitation would likely involve executing malicious code within the compromised host environment. The vulnerability demonstrates the importance of proper input validation and boundary checking in network services, particularly those that handle untrusted data from external sources. Organizations should note that the default configuration of VMware products does not enable IPv6 mode for VMNAT, making this vulnerability less likely to be exploited in environments where default settings are maintained. However, the risk remains significant for organizations that have explicitly enabled IPv6 functionality for their virtualized environments.
The recommended mitigations for this vulnerability include immediate patching of VMware Workstation and Fusion installations to the versions that contain the fix for this integer overflow condition. System administrators should also consider disabling IPv6 mode for VMNAT if this functionality is not required for their specific use cases, as this effectively eliminates the attack vector without requiring software updates. Additionally, network segmentation and monitoring should be implemented to detect anomalous network traffic patterns that might indicate exploitation attempts. Organizations should also conduct regular vulnerability assessments to identify any other potentially vulnerable network services or components that might present similar integer overflow risks. The vulnerability serves as a reminder of the critical importance of maintaining up-to-date security patches and the necessity of following security best practices in virtualized environments where the attack surface can be significantly expanded through proper configuration management.